There exist a wide variety of disinfecting compositions for eliminating microorganisms on inanimate surfaces. Many of these disinfecting compositions include toxic and poisonous chemicals that can cause serious effects on human health and our environment. When these disinfecting compositions are used on hard and inanimate surfaces such as counters and food preparation areas, bathroom fixtures, furniture and toys, precaution must be taken to ensure that the disinfecting compositions are rinsed off properly so that no residual toxic and poisonous chemicals remain on the surfaces. Further, with the use of synthetic chemicals, after extensive usage of these disinfecting compositions, the microorganisms have been shown to build up a tolerance or resistance to some of these synthetic chemicals, which reduces the efficacy of the disinfecting compositions. Moreover, synthetic chemicals can persist in the environment, which can be deleterious.
Some antimicrobial products containing naturally occurring essential oils are known to have antimicrobial properties. These products have been found to be effective in reducing or eliminating some microorganisms, typically those of vegetative bacteria and lipid or medium-sized viruses. However, since essential oils based antimicrobial products are not generally known to be effective against a wide spectrum of microorganisms, they are typically classified as sanitizers or perhaps as low-level or limited efficacy disinfectants by government regulatory bodies such as the United States Environmental Protection Agency (U.S. E.P.A.) or Health Canada. In order to achieve higher efficacy classifications such as hospital disinfectant, fungicide or tuberculocide, many of the available essential oils based antimicrobial products include synthetic co-actives such as quaternary ammonia, chlorine, phenol, alcohol, peroxides or acids. However, these synthetic co-actives are generally hazardous to the environment and have a negative impact on human health. As a result of the safety profiles of these synthetics, precautions need to be taken during handling and processing. In some instances, personal protective equipment is required when using these chemicals and stringent practices need to be followed when removing residues of these synthetics.
Still further, because essential oils are hydrophobic, they are not readily miscible in water. Often, a macroemulsion, a multiphasic or a viscous liquid is formed, which makes the essential oils difficult to process and poses problems when attempts are made to incorporate them into an aqueous solution. Due to the immiscibility of the essential oils into solution, aqueous antimicrobial compositions formulated with essential oils can be unstable, which results in an antimicrobial product with a short shelf life and poor aesthetic appeal. The immiscibility also contributes to the slow delivery of the essential oils to the microorganisms, thus leading to poor, slow or inconsistent killing results. In many instances, large concentrations of naturally occurring essential oils are required to achieve sufficient antimicrobial efficacy. Consequently, essential oils based antimicrobial products tend to be expensive.
U.S. Pat. Nos. 6,346,281 and 6,846,498 issued to the present inventor disclose aqueous antimicrobial compositions formulated with essential oils that are particularly effective at disinfecting and sanitizing inanimate surfaces. One of these compositions comprises about 0.5% to 10% by volume of a mixture of four essential oils, namely thyme oil, lemongrass, clove oil and eucalyptus oil, in a water carrier. Another of these compositions comprises about 0.5% to 10% by volume of at least one of the aforesaid essential oils and 1 to 1000 ppm of an ion agent such as copper sulfate that enhances the antimicrobial properties of the mixture of essential oils. Both of these compositions also require about 2 to 12% by volume of an organic solvent such as ethyl alcohol, hexadecane, n-propanol and ethyl acetate to disperse the essential oils into the water carrier. However, relatively large concentrations of each of the essential oils are required to provide these compositions with sufficient antimicrobial efficacy. Also, while both of these antimicrobial compositions are effective against a wide variety of gram negative and gram positive bacteria, they have not been demonstrated to be effective against some other types of microorganisms. Furthermore, the presence of clove oil in some of these compositions results in residue build-up on the inanimate surfaces and a strong, long-lasting fragrance that is not pleasing to some consumers.
Accordingly, there remains a need for improved disinfecting compositions that are environmentally sustainable, completely botanical or natural, biodegradable, non-toxic and capable of providing a broad disinfecting spectrum, and that utilize relatively low concentrations of a limited number of naturally occurring essential plant oils. There is also a need for improved essential oils based compositions that disperse the essential oils well in a water carrier, that do not require wiping or rinsing off after being applied to inanimate surfaces, and that are stable, have a long shelf life and are affordable and aesthetically appealing to consumers.